Final answer:
The change in gravitational potential energy of a 15kg post driver lifted by 70 cm is 102.9 joules, using the formula GPE = mgh with m = 15 kg, g = 9.8 m/s², and h = 0.7 m.
Step-by-step explanation:
Calculating Change in Gravitational Potential Energy
To calculate the change in gravitational potential energy (GPE) when an object is lifted, use the formula GPE = mgh, where m is the mass of the object, g is the acceleration due to gravity (approximately 9.8 m/s² on Earth), and h is the height the object is lifted.
In this case, a 15kg post driver is lifted by 0.7 meters (since 70 cm equals 0.7 meters). Therefore, the change in GPE would be calculated as follows:
The change in GPE is:
GPE = 15 kg × 9.8 m/s² × 0.7 m = 102.9 J (joules)
Therefore, the change in gravitational potential energy of the post driver when lifted by 70 cm is 102.9 joules.